In the field of computer networking and other packet-switched telecommunication networks, quality of service (QoS) refers to an ability to provide different priority to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow. For example, a QoS scheme may guarantee a required bit rate, delay, jitter, packet dropping probability and/or bit error rate. QoS guarantees are important for real-time streaming multimedia applications that are delay sensitive and have fixed bit rates, such as voice over IP, online games and video.
In processors with multiple cores, a host or software will often view the processor as one machine despite the processor having multiple cores. When the host or software runs several simultaneous processes, it will treat the processor as one machine, when it could be advantageous to treat it as multiple machines for the multiple processes. Few hardware mechanisms currently exist that regulate QoS of instructions from a host or software.